[Amps] TL922 Bias Modification

[Bryan Swadener]

 Let's look at some numbers...
Two 3-500Zs are going to pull 5V x 14.5A (each, 145W total) just to light the filaments whenever the amplifier is ON (even with zero anode current.
Assuming 3KV anode voltage at 150mA, we have about 450W of 'idle' power. But, that happens only during TX. Averaged over the entire ON time, the value is much less.
Then, a "VOX" circuit to cutoff anode current when there's no RF drive might not save as much as you might want. It might be just as easy and/or cheap to improve ventilation. I recall when I first ran my SB-220. I had it VERY close to an openable window.
vy 73,Bryan WA7PRC
    On Saturday, May 18, 2019, 3:45:26 PM PDT, Jim <jimw7ry at gmail.com> wrote:  
   Why do you think you need such a thing Joe?
Thanks
73
Jim W7RY On 5/16/2019 11:23 PM, Joe wrote:
  
 Has anyone installed one of these into their SB-220?
 
 http://www.ameritron.com/Product.php?productid=EBS-1H
 
 Joe WB9SBD
 
  On 5/10/2019 7:55 PM, Jim wrote:
  
I tried to post a schematic and the moderator wont allow it for some unknown reason. 
 
 Schematic is attached. 
 
 
 Thanks 
 73 
 Jim W7RY 
 
 On 5/10/2019 9:52 AM, Lou Everett, Sr. wrote: 
 
Where is it? 
 
 Lou WA5LOU 
 
 On Fri, May 10, 2019 at 7:41 AM Jim <jimw7ry at gmail.com <mailto:jimw7ry at gmail.com>> wrote: 
 
     Here is the modification (simple schematic) to the cut-off bias in 
     the 
     Kenwood TL-922 amplifier. 
 
 
     --     Thanks 
     73 
     Jim W7RY 
 
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 -- 
 Lou WA5LOU 
 
 ** 
 

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